msc {
  # options
  wordwraparcs=on,
  arcgradient="10",
  hscale = "2.5";

  # entities
  a [label="Device"],
  b [label="Server"];

  # arcs
  a => b [label="TLS[ RFID_TAG, JWT(_id) ]"];
  b => b [label="VERIFY(JWT)"];
  b >> a [label="TLS[ If(JWT invalid) status 401 ]"];
  b =>> b [label="VERIFY (_id and RFID_TAG)"];
  b >> a [label="TLS[ STATUS 200 OR 401 ]"];
   ---  [ label = "If status 200 ", ID="1" ];
  a =>> a [label="Unlock_PIN_input()"];
  a => b [label="TLS[ RFID_TAG, PIN, JWT(_id)]"];
  b => b [label="If {RFID_TAG, PIN} in db 200 else 401"];
  b >> a [label="TLS[ STATUS 200 || 401 ]"];
  ---  [ label = "If status 200 ", ID="2" ];
  a =>> a [label="Unlock_Door()"];
}